Security blanket



FIG. 1 is a top plan view of a security blanket embodying my design, the dash lines indicating stitches;

FIG. 2 is a bottom plan view thereof;

FIG. 3 is a lower side elevational view thereof;

FIG. 4 is a left end view thereof;

FIG. 5 is an upper side elevational view thereof; and,

FIG. 6 is a right end view thereof. 

The ornamental design for a security blanket, as shown and described. 